Many vehicles include transmissions, which couple a power source, such as an internal combustion engine, to one or more differentials or axles connected to wheels or other ground engagement apparatus. Transmissions use gears to provide speed and torque variations from a power source to a differential or axle. Transmissions may include one or more vents to allow air to flow into and out of the transmission or drivetrain in order to maintain atmospheric pressure within the transmission or drivetrain.